/*
 * Copyright 2002-2017 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.util.xml;

import java.util.ArrayList;
import java.util.List;
import java.util.Map;

import javax.xml.namespace.QName;
import javax.xml.stream.Location;
import javax.xml.stream.XMLEventFactory;
import javax.xml.stream.XMLEventWriter;
import javax.xml.stream.XMLStreamException;
import javax.xml.stream.events.Attribute;
import javax.xml.stream.events.Namespace;

import org.xml.sax.Attributes;
import org.xml.sax.Locator;
import org.xml.sax.ext.LexicalHandler;

import org.springframework.lang.Nullable;

/**
 * SAX {@link org.xml.sax.ContentHandler} and {@link LexicalHandler}
 * that writes to a {@link javax.xml.stream.util.XMLEventConsumer}.
 *
 * @author Arjen Poutsma
 * @since 4.0.3
 */
class StaxEventHandler extends AbstractStaxHandler {

    private final XMLEventFactory eventFactory;

    private final XMLEventWriter eventWriter;


    /**
     * Construct a new instance of the {@code StaxEventContentHandler} that writes to the
     * given {@code XMLEventWriter}. A default {@code XMLEventFactory} will be created.
     *
     * @param eventWriter the writer to write events to
     */
    public StaxEventHandler(XMLEventWriter eventWriter) {
        this.eventFactory = XMLEventFactory.newInstance();
        this.eventWriter = eventWriter;
    }

    /**
     * Construct a new instance of the {@code StaxEventContentHandler} that uses the given
     * event factory to create events and writes to the given {@code XMLEventConsumer}.
     *
     * @param eventWriter the writer to write events to
     * @param factory the factory used to create events
     */
    public StaxEventHandler(XMLEventWriter eventWriter, XMLEventFactory factory) {
        this.eventFactory = factory;
        this.eventWriter = eventWriter;
    }


    @Override
    public void setDocumentLocator(@Nullable Locator locator) {
        if (locator != null) {
            this.eventFactory.setLocation(new LocatorLocationAdapter(locator));
        }
    }

    @Override
    protected void startDocumentInternal() throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createStartDocument());
    }

    @Override
    protected void endDocumentInternal() throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createEndDocument());
    }

    @Override
    protected void startElementInternal(QName name, Attributes atts,
            Map<String, String> namespaceMapping) throws XMLStreamException {

        List<Attribute> attributes = getAttributes(atts);
        List<Namespace> namespaces = getNamespaces(namespaceMapping);
        this.eventWriter.add(
                this.eventFactory.createStartElement(name, attributes.iterator(), namespaces.iterator()));

    }

    private List<Namespace> getNamespaces(Map<String, String> namespaceMapping) {
        List<Namespace> result = new ArrayList<>();
        namespaceMapping.forEach((prefix, namespaceUri) ->
                result.add(this.eventFactory.createNamespace(prefix, namespaceUri)));
        return result;
    }

    private List<Attribute> getAttributes(Attributes attributes) {
        List<Attribute> result = new ArrayList<>();
        for (int i = 0; i < attributes.getLength(); i++) {
            QName attrName = toQName(attributes.getURI(i), attributes.getQName(i));
            if (!isNamespaceDeclaration(attrName)) {
                result.add(this.eventFactory.createAttribute(attrName, attributes.getValue(i)));
            }
        }
        return result;
    }

    @Override
    protected void endElementInternal(QName name, Map<String, String> namespaceMapping) throws XMLStreamException {
        List<Namespace> namespaces = getNamespaces(namespaceMapping);
        this.eventWriter.add(this.eventFactory.createEndElement(name, namespaces.iterator()));
    }

    @Override
    protected void charactersInternal(String data) throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createCharacters(data));
    }

    @Override
    protected void cDataInternal(String data) throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createCData(data));
    }

    @Override
    protected void ignorableWhitespaceInternal(String data) throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createIgnorableSpace(data));
    }

    @Override
    protected void processingInstructionInternal(String target, String data) throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createProcessingInstruction(target, data));
    }

    @Override
    protected void dtdInternal(String dtd) throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createDTD(dtd));
    }

    @Override
    protected void commentInternal(String comment) throws XMLStreamException {
        this.eventWriter.add(this.eventFactory.createComment(comment));
    }

    // Ignored

    @Override
    protected void skippedEntityInternal(String name) throws XMLStreamException {
    }


    private static final class LocatorLocationAdapter implements Location {

        private final Locator locator;

        public LocatorLocationAdapter(Locator locator) {
            this.locator = locator;
        }

        @Override
        public int getLineNumber() {
            return this.locator.getLineNumber();
        }

        @Override
        public int getColumnNumber() {
            return this.locator.getColumnNumber();
        }

        @Override
        public int getCharacterOffset() {
            return -1;
        }

        @Override
        public String getPublicId() {
            return this.locator.getPublicId();
        }

        @Override
        public String getSystemId() {
            return this.locator.getSystemId();
        }
    }

}
